Introduction to Food Preservation

• Food preservation is a process that prevents food and vegetables from spoiling while maintaining their color, taste, and nutritive values.
• Preservation extends the shelf life of food products.

Why Food Preservation is Important

• Food preservation retains food over time without contamination from pathogens or chemicals.
• It ensures the food retains its color, texture, flavor, and nutritional value.
• Food preservation prevents the growth of bacteria, fungi, and other microorganisms.
• It also retards the oxidation of fats, preventing rancidity.

Introduction to Food Preservation

• Food preservation maintains desired food properties for as long as possible.
• In most countries, innovation, sustainability, and safety are key focuses in the food industry.
• Food safety is the top priority in food production and preservation.
• Compromises can be made on qualities like color, but not on safety.
• Modern food preservation is complex and involves continuous development of new techniques.
• These techniques consider economic preservation, consumer satisfaction, nutritional and sensory aspects, convenience, safety, minimal chemical preservatives, price, and environmental safety.
• Understanding the effects of each preservation method is critical.
• Food preservation seeks to minimize microbial spoilage and extend shelf life.
• Preservation considers the entire food chain, including growing, harvesting, processing, packaging, and distribution.
• An integrated approach is essential.
• It is central to food science and technology, serving as the primary purpose of food processing.

Key Considerations in Food Preservation

• Identifying which properties or characteristics of a food need preserving is important.
• A property that is beneficial for one product can be detrimental to another, like collapse and pore formation during drying.
• In the case of breakfast cereal ingredients, crust formation is desirable.
• Quick rehydration is necessary for instant soup ingredients.
• Consumers expect apple juice to be clear, while orange juice may be cloudy.
• Main reasons for food preservation:
• To overcome inappropriate agriculture planning.
• To produce value-added products.
• To preserve quality and nutritive value.
• To prevent spoilage and eliminate waste.
• To provide diet variety.
• Important points to consider in food preservation include:
• The desired level of quality.
• The preservation length.
• The target consumer group.

Food Types

• Perishable foods last for less than 2 days to 1 week (e.g., fruits, milk, vegetables, meat).
• Semi-perishable foods last around 2 months and are processed (e.g., ice cream, cheese, bread, cake, pastries).
• Shelf-stable foods have a longer shelf life, more than 6 months (e.g., food grains).

Preservation Duration

• After a storage period, food’s qualities may become undesirable, making it unsuitable for consumption, the end of its shelf life..
• Manufacturers define this based on when the product remains saleable, setting a "best before" date shorter than actual shelf life.
• Measuring the change rate of a quality attribute is important when studying shelf life.
• Product quality includes appearance, yield, eating, and microbial characteristics to ensure consumer pleasure.
• Preservation length relies on the intended purpose.
• For meals prepared for lunch, a short shelf life (half a day to one day) suffices, making long-term preservation unnecessary.
• Foods for space travelers/wartime storage need long shelf lives (3-5 years).

Factors Affecting Food Quality

• Quality
• Safety
  • Level of micro-flora
  • Pathogens
  • Microbial toxins
  • Parasites
  • Toxic chemicals
  • Radioactive hazards
• Choice
  • Advertisement
  • Public Knowledge
  • Social Factor
  • Economic factor
  • Consumer age
  • Media report
  • Past experience
  • Attitude
  • Expectation
  • Sensory
  • Nutritive
  • Functional
  • Convenience

Target Consumer

• Knowing the target consumer is crucial because of varying nutritional needs and food restrictions among different demographics.
• Food poisoning can be fatal, especially in infants, pregnant women, the elderly, and those with depressed immune systems.
• Legal aspects of preservation differ for human versus animal consumption.
• Considering the target consumer group during manufacturing is important.

Causes of Deterioration

• Mechanical, physical, chemical, enzyme, and microbial effects are major causes of food deterioration and spoilage.
• Damage during harvesting, processing, or distribution can reduce shelf life.
• Examples of deterioration:
• Bruising of fruits/vegetables leading to rot.
• Tuberous/leafy vegetables losing water and wilting in low humidity.
• Dried foods absorbing moisture and becoming soggy in high humidity.
• Microbial contaminants come from soil, water, air, and animals (insects, rodents, and humans).
• Mechanical damage facilitates spoilage and further chemical/microbial deterioration.
• Microbial growth leads to spoilage, undesirable sensory changes, and potential safety hazards.
• Chemical changes during processing/storage degrade sensory and nutritional quality.
• Enzymatic reactions can degrade food with phenolase in fruits.

Major Quality-Loss Mechanisms

• Microbiological: Microorganism Growth and Toxin Production
• Enzymatic: Browning and Off-Flavor
• Chemical: Color Loss, Flavor Loss, Nonenzymatic Browning, Nutrient Loss, Oxidation-Reduction, and Rancidity
• Physical: Collapse, Controlled Release, Crystallization, Flavor Encapsulation, Phase Changes, Recrystallization, Shrinkage, and Transport of Component
• Mechanical: Bruising Due to Vibration and Cracking Damage Due to Pressure

Principles of Food Preservation

• Inhibit the growth and activity of microorganisms.
• Practice asepsis.
• Remove microoganisms.
• Regulate temperatures, drying, and chemicals.
• Destroy microorganisms (heating or radiation)
• Protect against self-decomposition.
• Inhibit enzyme activity.
• Delay or inhibit chemical reactions.
• Protect from spoilage from insects and rodents
  • Preserve food soon after preparation, without allowing the food to stand for a long time
• Protect against losses caused by mechanical methods

Importance of Food Preservation

• Preserving is important and vital to the food industry due to psychological, social, and health factors.
• It extends shelf life, retains quality, flavor and increases supply, and adds food variety.
• Food Preservation decreases food wastage and makes food available year-round.

Food Preservation Methods

• Preservation methods depend on the food items and quantity to be preserved.
• Food preservation classifies broadly into:
• Bactericidal methods - kills bacteria.
• Bacteriostatic methods - inhibits bacterial growth.
• Categorization of food preservation techniques based on mode of action:
• Inhibition of microbial growth
• Slowing chemical deterioration
• Direct inactivation of bacteria, yeasts, or enzymes
• Avoiding recontamination
• Preservation begins when foods are harvested or separated from their immediate growth medium.

Food preservation methods

• Inhibition method includes low temperature storage, reduction of water activity, decrease of oxygen, increase of carbon dioxide, acidification,fermentation, adding preservatives, adding antioxidants, control pH, freezing, drying, concentration, surface coating, structural modifications, chemical modifications, gas removal, changes in phase transition, and hurdle technology.
• Inactivation method includes sterilization, pasteurization, irradiation, electrifying, pressure treatment, blanching, cooking, frying, extrusion, light, sound, and magnetic field.
• Avoid recontamination method includes Packaging, Hygienic processing, Hygienic storage, Aseptic processing, HACCP, GMP, ISO 9000, TQM, and risk analysis and management.
• Preservation methods hinge on whether the food originates from plants or animals.
• Handling of plant-based post-harvest foods involves controlling the environmental atmosphere like humidity, gas composition, temperature, packing, storing, and transport.
• Physical treatments include curing, pre-cooling, temperature treatments, cleaning, and waxing.
• Chemical treatments include disinfection, fumigation, and dipping.
• Postharvest meat quality depends on animal slaughter conditions and pre-death stress.
• Fish preservation includes chilling, electrical stimulation, decontamination, hot water rinsing with or without chlorination, phosphate decontamination, hydrogen peroxide, chlorine, chlorine dioxide, ozone, and organic acids for surface treatment.
• Physical/chemical pretreatments such as blanching and sulfiting prepare food for major preservation.
• The purpose of pretreatment enhances product quality and process efficiency.

Inhibition Methods

• Chilling/storing below 5°C is a popular preservation method.
• Inhibition methods:
  • Control the external environment (temperature, relative humidity).
  • Control intrinsic properties (water activity or pH).
• Danger zone for microbial growth: 5°C - 60°C.

Preservation from chemicals/additives.

• Chemicals/additives that preserve:
  • pH regulators
  • anti-microbes
• anti-oxidants
• Preservatives are either extracted as natural source or made synthetically.
• Safe consumption relies on the function in a food and risk-benefit analysis.

Common Substances for Chemical Antimicrobial Food Processing

• Acetic acid salt acts against bread bacteria and molds, to be used as vinegar in pickled product and mayonnaise
• Benzoic acid salt acts against jams, syrups and orange juice product yeast and molds, to be used in ketchup
• Na and Ca propionate acts against cake, cheese and bread yeast and molds,
• Potassium sorbate acts against bread bacterial and molds
• Salt acts against canned and baked bacterial, yeast and mold.
• Sodium nitrite acts against meat bacterial yeast and mold.
• Sodium benzoate acts against fruits and condiments bacterial, yeast and mold.
• Sugar acts against preserves, baked goods and fruit bacterial, yeast and mold.
• Sulfite and sulfur dioxide acts against lemon juice and wines, bacterial, yeast and mold.

Controlling Water

• Water activity, not total water, leads stability due to microorganisms.
• Foods need a minimum water activity of .6-.7 so microorganisms cannot reproduce..
• Pathogenic bacteria need above .85 or .86, yeast and molds need above .80 to grow.
• Removing water, adding solutes, or changing solute-water interactions reduces food's water activity.

Controlling Atmosphere

• Controlled atmosphere or MAP technique minimizes decay by changing air composition.
• The gas does not is not monitored in a MAP package.
• In CAP scrubbing is used to monitor and adjust altered gas in packaging.
• Gases can be absorbed or released to control aroma.
• Volatiles are oxygen, CO2 ethylene, or water.

Inactivation

• For thermal inactivation thermal heating is used.
• Thermally processed foods have very long shelf life.
• Heat can provide tender cooked flavors and taste.
• The majority of spoilage microorganisms are heat-labile..
• Heat is safe and chemical-free.
• Overcooking can lead to unwanted disintegration.

High Pressure & Ultrasound

• High-pressure processing inactivates vegetative microorganisms by isostatic pasteurization (1000-9000 atmospheres).
• The basis of high hydrostatic pressure relies on changes, reactions, and phase transition volume.
• Energy from ultrasound is sound energy with a 20 kHz frequency.
• Ultrasound is for characterizing food materials and processes and directly preserving/processing food.

Electricity & Radiation

• Electricity in form of ohmic heating, microwave, high-voltage arc discharge can be used for food preservation.
• In irradiation, energy transfers to electrons and creates positive and negative molecules.
• The radiation destroys cell structures of insects, bacteria, and molds.

Hurdle Technology

• Pathogen Control from hurdles maintains food safety and shelf life by ensuring pathogens eliminated.
• Many hurdles include storing and processing at high or low temperature, or preservatives lowering redox potential.

Food Safety Concepts

• "Hazard Analysis Critical Control Point" HACCP identifies and evaluates hazards to meet 7 principles, and ensure food safety.
• Chemical, biological hazards cause illness and injury from control points.
• Corrective actions follow the 6 HACCP processes.
• Procedures to guarantee manufacturing safety are Good Manufacturing Practices (GMP).
• A safe work environment along with food that is safe and wholesome must be sustained.
• Ground, equipment, trained people, product recall and process control.
• Critical procedures and practices made safe for food are followed in the standard Operating procedures (SOPs).
• To modernize equipment so that errors do not occur customer satisfaction must be achieved.
• Quality is managed under the TQM (Total Quality Management) concept.
• Edwards Demming conceptualized the project to lower errors produced during customer satisfaction and mechanized service
• Errors are restricted to one per one million units.
• Food safety is associated with ISO 22000 and borne risks.
• ISO 9000 relates to customer needs.
• Standard of ISO 22000 includes these elements: system management is interactive and communication, prerequisites for HACCP.